Gas turbines are widely used in industrial and power generation operations. A typical gas turbine may include a compressor section, a combustion section disposed downstream from the compressor section, and a turbine section disposed downstream from the combustion section. A working fluid such as ambient air flows into the compressor section where it is progressively compressed before flowing into the combustion section. The compressed working fluid is mixed with a fuel and burned within one or more combustors of the combustion section to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases flow from the combustors and expand through the turbine section to produce thrust and/or to rotate a shaft, thus producing work.
In a particular combustor design, the combustor includes one or more bundled tube fuel injectors that extend axially downstream from an end cover. The bundled tube fuel injector generally includes a fuel distribution module and a tube bundle having a plurality of pre-mix tubes that are in fluid communication with the fuel distribution manifold. The pre-mix tubes are arranged radially and circumferentially across the bundled tube fuel injector. The pre-mix tubes extend generally parallel to one another downstream from the fuel distribution manifold.
An outer shroud extends circumferentially around the pre-mix tubes downstream from the fuel distribution manifold. A support plate is disposed substantially adjacent to the fuel distribution manifold and the plurality of pre-mix tubes extends axially through the support plate towards an aft end of the bundled tube fuel injector. An aft plate or effusion plate extends radially and circumferentially across a downstream end of the outer shroud. A downstream or end portion of each pre-mix tube extends through the aft plate such that an outlet of each tube is downstream from a hot side surface of the aft plate, thus providing for fluid communication into the combustion chamber or zone.
In conventional bundled tube fuel injectors, the aft plate is connected to the bundled tube fuel injector by welding an outer perimeter of the aft plate to the downstream end of the outer shroud. In addition, a collar portion of the aft plate is welded or brazed to a cooling air flow sleeve that extends axially downstream from the support plate. The collar and the cooling air flow sleeve at least partially define a cartridge passage for inserting a fuel and/or air cartridge through the bundled tube fuel injector.
Although the weld joint formed at the collar and air flow sleeve joint is generally effective for retaining the aft plate to the bundled tube fuel injector, the weld joint is costly to manufacture due to various weld-prep operations required and may be generally difficult to weld due to a limited working area. In addition, removal of the aft plate for inspection, repair and/or replacement is time consuming and costly due to grinding, blending and/or other repair operations required to break the weld joint and prepare the parts for reassembly. Therefore, an improved bundled tube fuel injector would be useful.